Method for estimating a number of objects

A method for estimating a number of objects, the method to be implemented by a processing module, and being utilized to estimate a number of a plurality of objects having elongated shapes based on an image of the objects that contains substantially-circular end faces of the objects, the method comprising the steps of:

• generating a characteristic image based on the image of the objects, the characteristic image containing a plurality of characteristic patterns which are associated with the end faces of the objects;
• calculating, based on the characteristic image, a number of the characteristic patterns, an area of each of the characteristic patterns, and characteristic distances each of which is a distance between centers of respective adjacent two of the characteristic patterns
• calculating an estimated cross-sectional area for each of the objects based on at least the characteristic distances;
• calculating an additive quantity based on a ratio of the area of each of the characteristic patterns to the estimated cross-sectional area;
• and
• obtaining an estimated number of the objects based on at least the number of the characteristic patterns thus calculated and the additive quantity.